diff --git a/interfaces/SimpleScene/SimpleScene.proto b/interfaces/SimpleScene/SimpleScene.proto
index 5bc13ae255d9cdf4e6ad0cc0bb0b65bcdf37f1a4..74e1166bf4ae92d01382dffed34f84d68c469d24 100644
--- a/interfaces/SimpleScene/SimpleScene.proto
+++ b/interfaces/SimpleScene/SimpleScene.proto
@@ -53,8 +53,8 @@ message RefSystem {
 }
 
 message IposMonitoringRequest {
-  string frameId = 1; // deprecated
-  // repeated string frameIds = 1; // a monitoring request can be concerned with multiple overlapping frames
+  // frameId = 1; // deprecated
+  repeated string frameIds = 1; // a monitoring request can be concerned with multiple overlapping frames
   float delta = 2; // min. change in position to trigger a position update, setting delta and updateFrequency to -1 cancels the (existing) monitoring task
   float updateFrequency = 3; // defines how many times per second a PositionUpdateEvent is sent
   repeated string type = 4; // object-types to be observed; CeTI will send BOX,BIN,ZONE,ROBOT,HUMAN,OTHER